Optimization of purification method for 2,6-naphthalene dicarboxylic acid
In order to optimize the purification process of 2,6-naphthalene dicarboxylic acid(2,6-NDA),the impacts of alkali extraction acid precipitation,solvent recrystallization and activated carbon adsorption decolorization on the purification effect of 2,6-NDA were investigated,and the most suitable process conditions were determined.The results showed that both alkali extraction acid precipitation and solvent recrystallization could effectively improve the purity of 2,6-NDA products,but the 2,6-NDA particles formed by the alkali extraction acid precipitation process were very small in size,difficult to filter,and not suitable for large-scale industrialization.The recrystallization effect of N,N-dimethylacetamide(DMAC)was better than that of N,N-dimethylformamide(DMF).Activated carbon had a good adsorption and removal effect on cobalt and manganese ions and their complexes formed with 2,6-NDA.The weak alkali environment was more favorable for the activated carbon to play its role in the process of alkali extraction acid precipitation.However,there was a problem of high consumption of activated carbon and serious product loss.Thus,activated carbon was not necessary for DMAC solvent recrystallization.
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